The working hypothesis to be tested is that the plasma membrane of the prostate cell functions, both as a receptor to bind androgen, and as a transducer of androgen stimulation: Intrinsic Na+, K+-ATPase of the membrane is androgen- stimulable and ouabain-inhibitable. Changes in rates of Na+, K+- ATPase, and a coupled Na+-citrate cotransporter, set the pace of glycolysis and citricogenesis through the consequences of a) an increased ADP/ATP ratio and a decreased cytosolic citrate concentration on glycolysis; b) increased Na+ influx with cell alkalinization and facilitated cotransport of substrates (glucose, amino acids) in response to the pump-mediated Na+ efflux. Five protocols, all describing experiments to be performed on monolayera or suspensions of cultured human prostatic epithelial cells, will test the effects of three levels of testosterone and two levels of ouabain on lacticogenesis; the hormone-sensitivy of donors of acetyl CoA (glucose, pyruvate, palmitate) and oxaloacetate (glucose via pyruvate, aspartate via transamination, TCA cycle via succinate), citricogenesis; whether citricogenesis is a requirement for or a consequence of the proposed mechanism; the dependence of metabolic activity on Na+ flux and alkalinization. The answers will be sought in analyses of bulk flow of metabolites (by specific enzymatic assays) between mitochondria, cytosol and medium, and distribution of radiolabeled products isolated from the 3 compartments by ion exchange and thin layer chromatography.